Endoscopic Diagnosis of Epithelial Subtypes of Superficial Non-Ampullary Duodenal Epithelial Tumors using Magnifying Narrow-Band Imaging.

Introduction: Superficial non-ampullary duodenal epithelial tumors (SNADETs) include low-grade adenoma (LGA) and high-grade adenoma or carcinoma (HGA/Ca) and are classified into two different epithelial subtypes, gastric-type (G-type) and intestinal-type (I-type). We attempted to distinguish them by endoscopic characteristics including magnifying endoscopy with narrow-band imaging (M-NBI).

Methods: Various endoscopic and M-NBI findings of 286 SNADETs were retrospectively reviewed and compared between G- and I-types and histological grades. M-NBI findings were divided into four patterns based on the following vascular patterns; absent, network, intrastructural vascular (ISV), and unclassified. Lesions displaying a single pattern were classified as mono-pattern and those displaying multiple patterns as mixed-pattern. Lesions showing CDX2 positivity were categorized as I-types and those showing MUC5AC or MUC6 positivity were categorized as G-types based on immunohistochemistry.

Results: Among 286 lesions, 23 (8%) were G-type and 243 (85%) were I-type. More G-type lesions were located oral to papilla (91.3 vs. 45.6%, p < 0.001), and had protruding morphology compared to those of I-types (65.2 vs. 14.4%, p < 0.001). The major M-NBI pattern was ISV in G-type (78.2 vs. 26.3%, p < 0.001), and absent for I-type (0 vs. 34.5%, p = 0.003). Three endoscopic characteristics; location oral to papilla, protruding morphology, and major M-NBI pattern (ISV) were independent predictors for G-type. Mixed-pattern was more common in HGA/Ca than LGA for I-type (77.0 vs. 58.8%, p = 0.01); however, there was no difference for those in G-type.

Conclusion: Endoscopic findings including M-NBI are useful to differentiate epithelial subtypes.